where \(i,j=x,y\)  denote two transverse directions. The result of (REF )
is consistent with Ref. [1]}.  We can also use the light-cone coordinate and obtain
\(L^{-\nu }(p_{1},p_{2},k_{1},k_{2}) & = & -\frac{p_{1}^{-}L^{+\nu }-p_{1}^{i}L^{i\nu }}{p_{1}^{+}},\nonumber \\L^{\mu +}(p_{1},p_{2},k_{1},k_{2}) & = & -\frac{p_{2}^{+}L^{\mu -}-p_{2}^{j}L^{\mu j}}{p_{2}^{-}}.\) 
